The present invention relates to a jitter control apparatus for a video camera, and more particularly, to a jitter control apparatus for a video camera for preventing jitter of the screen caused by vibrations of the hands of the user.
It is difficult to videotape with recently developed home video cameras designed to be hand held without a support such as a tripod since there are jitters on the screen due to vibrations of the hands of the user.
To account for such a problem, a conventional jitter control apparatus for a video camera includes a variable angle prism respectively shown in FIGS. 1A through 1C. Referring to FIG. 1A, a variable angle prism 10 arranged on a light path is comprised of a pair of glass plates 11 and 13 and a bellows 14. The bellows 14 is formed of a resin such as polyethylene and are fixed so as to connect the frames of the two glass plates 11 and 13. An enclosed inner space is formed between the two glass plates 11 and 13. The bellows 14 can be folded or unfolded by an external force. The inner space between the two glass plates 11 and 13 is filled with a transparent fluid 12 such as silicon oil.
In the operation of the variable angle prism having the above structure, referring to FIG. 1B, when the two glass plates 11 and 13 are parallel, the angle of incidence and the angle of emission of light 16 are the same. However, as shown in FIGS. 1A and 1C, when a predetermined angle is generated between the two glass plates 11 and 13, light 15 and 17, respectively, refracts at a predetermined angle, passing through the two glass plates 11 and 13.
The vibrations of the hands of the user is sensed by a sensor (not shown). The angle between the glass plates 11 and 13 is controlled by driving an actuator (not shown) for driving the glass plates 11 and 13 according to the sensed signal. Therefore, jitters of the screen due to vibrations of the hands can be prevented by differentiating the angle of emission of the light passing through the glass plates 11 and 13 from the angle of incidence.
However, since the apparatus for preventing jitters of a video camera is operated by folding or unfolding the bellows 14, the bellows 14 may break after prolonged use and the liquid 12 between the glass plates 11 and 13 may leak and contaminate the inside of the camera. Also, it is difficult to assemble and manufacture the apparatus.